Rubber spring



July l20, 1948. R. w. BROWN 2,445,723 RUBBER SPRING l Filed March l,1944 3 Sheets-Shet 1 QOY W- BROWN July 20, 1948. R. w. BRowN 2,445,723

RUBBER. SPRING Filed March l, 1944 ,3 Sheets-Sheet 2Llll'lllllflllllllllll All \\\\\\\\\\\\\\\\\YRA\\\\\ w gpfw July 20,1948. R. w. BROWN 2,445,723

RUBBER SPRING Filed Hatch 1. 1944 5 Sheets-Sheet 3 gummi/bof ROY w.bRowN Pareated July 20,

Roy W. Brown,

aman srnrNG v Akron, Ohio, signor to The Firestone Tire ltnbber Company,Akron, Ohio, a

corporation o! Ohio Application March l, 1944, Serial No. 524,829

14 Claims.

'Ihis invention relates to rubber springs, and

moreparticularly to rubber springs of a type adapted for use in aircraftlanding gears and vehicular suspension members generally, as forexample, e. rubber spring adapted to -be interposed between the chassisand the body of an automobile; or between the arms of a suspensionparallelogram of a bogie wheel mounting in which half tracks areemployed; or between the arms of a parailelogram of an automobilemounting. 1 The present invention consists generally of'a plurality ofopen center cone shaped discs arranged in stack formation in cuppedrelation, the discs being composed of a rubber. body portion attached toa strong rigid end plate.

'Ihe invention is disclosed by illustrations of specific embodimentsthereof, lbut it is to be understood that the invention contemplates theuse of the rubber spring embodying the invention in whatever form andwherever it may be found useful in accomplishing its objects. It is alsoto be understood that "rubber as used in the present specification andclaims, includes synthetic rubbers andl rubber-like plastics, onedetailed classification oi which will be found by reference to Harry L.Fisher, Industrial Engineering Chemistry, volume 31, page 941 (1939).

An object of the present invention is to provide a rubber springconsisting of a plurality of rubber discs which are so shaped as to beselfstabilizing when the discs are stacked one upon the other. l

Another object of the invention is to provide a rubber spring consistingof a plurality of open center rubber discs mounted about a centralsupport tube `which discs have shock absorber medium on their inner tubecontacting surface. Y

under an extreme compressed condition of the disc.

Yet another object ofthe invention is to provide a rubber spring ofsubstantial strength with a longitudinal central bore therethrough whosesidewalls will not buckle outwardly' when the spring is subjected tosevere longitudinal compression.

Another object of the invention is to suppo the rubber of a rubberspring in a manner which enables the rubber to support a heavier loadthan it would otherwise support.

It is another object of the inventiony to provide Aa rubber springwherein greater resistance is provided to the compression than to theexpansion or -vided to one stroke than to its opposite stroke.

A further object of the invention is to provide a rubber spring thatcompresses relatively easily at the beginning of a compression stroke,but` `i'i still further object of the invention is to provide a rubberspring in which worn parts may be replaced.

Other objects and advantageswill be apparent to those familiar with theart as reference is had to the accompanying drawings wherein theinvention is illustrated and wherein:

Fig. 1 is a diametric sectional view'of a rubber spring embodyingy theinvention shown in a mounting adapted for use in an airplaneV landinggear, the spring being shown in its unstressed condition;

Fig. 2 isa section similar to Fig. 1 except the spring is shown in itscompressed position;

Fig. 3 is a bottom plan view of an individual spring disc;

Fig. 4 is a sectional view of a spring disc taken on line 4-4 of 1118.5;

Fig. 5 is a diametric section of a spring disc taken on the line B-l ofFig. 3:'

Fig. 6 is a. chart illustrating the-load deection curves of the spring;y

Fig. 'l is a side elevational view of a portion of a vehicle adapted torun on half-tracks, and a suspension device embodying the presentinvention operatively associated therewith;

Fig. 8 is an elevation of the structure shown in Fig. 'i as viewed fromthe left thereof, a part being broken away and in section;

Fig. 8a is an enlarged section through the r'ubber spring taken on line8a`8a of Fig. 8. the

. spring being shown under normal load:

which converts itself into a solid rubber bumper as the compressionstroke approaches its limit.

Fig. 9 is a fragmentary front elevation of a ,i motor vehicle, and arubber spring embodying the present invention Voperatively associatedtherewith, the spring being shown as a vertical suspension memberinter-positioned between the arms of a suspension parallelogram; and

Fig. 10 isa plan view of the structure shown in Fig. 9.

Referring now in more detail to Figs. 1, 2, 3, 4 and 5 of the drawings,it will be seen that an upper support plate or head il receives a cen- 3trai guide tube I| which is retained suspended in position by nuts I2and I2. The support head II is a part of the fuselage of an airplane. A

lower supporting plate or head Il having a cen.

trai opening therethrough is mounted about the guide tube and on thelanding gear, not shown, ot an airplane by means of attachment structureII to which structure the head Il is attached by means of bolts I2 andnuts I1. 'I'he structure Il hasan opening, not shown, through which thelower end of the tube may project a distance sufllcient to accommodatethe travel of head I4 in the compression and expansion stroke of arubber spring indicated generally as S. The spring S is composed of aplurality of conical discs 22, each having a central bore il. The

discs 22 consist of two concentric rubber rings' 2| and 22 ofsubstantial thickness. Said rubber rings have a coneshaped metallicplate 22 vulcanized to one end only thereof, the said rubber rings ofeach of said discs being radially spaced apart on said plate 22, saidrings defining in each disc a continuous circular groove 2l. In the formof the invention shown in Fig. 1- the groove 24 extends to the plate 22thus leaving no rubber connection between rings 2| and 22. It is to beunderstood however that a relatively shallow thickness of rubber at thebottom of said groove may connect said concentric rings if founddesirable or if it is found diillcult to avoid such rubber connection inmolding and vulcanizing said rings tol said plate. It is also to -beunderstood that the vertical side walls of the groove 24 shown in Fig. 5may be formed with a bulge, a recess, or otherwise modified, if founddesirable to improve the life or performance of the spring. Obviouslyadditional rings couldbe substituted for the two rings 2| and 22 withoutavoiding the spirit of the invention and such modifications are withinthe contemplations of the invention. It will be seen by reference toFigs. l and that the discs 22 are of a uniform thickness of rubberexcept at the radial inner edge of ring 2|. The radially inner edge ofeach of the rings 2| defines a tapered central bore and terminates in aportion 25 of a thickness progressively reduced from the thickness ofthe ring 2|, said portion 25 terminating in a blunt radially innersurface 26 of substantial width. A layer of fabric 21 is vulcanized tothe radial inner edge of the rubber portion of each of the rings 2|. Thefabric 21 forms the surface 22 and extends radially outwardlyvfor adistance from edges 2l and 25 of said surface .22. It is to be noted byreference to the drawing that the diameter of the central -bore I2 issmaller at the edge 2l than at the edge 2l. The fabric -21 may be of anytype found to be satisfactory, as for example, a cotton duck whichweighs I2 oz. to the square yard. The fabric may be prepared forapplication to the ring 2| by frictioning it on one side only in aregular rubberizing calendering operation: cutting it into proper sizestrips and'attaching the strips to the inner edge of the rubber of thering 2i before molding and vulcanization of said ring as will be readilyunder.- stood by those familiar with the manufacture of rubber products.The rubberized side of said rubberized fabric is ink contact with therubber of the ring 2| The periphery or outer marginal ausm l lameter ofthe central bore 2| is greater than the diameter of the central bore I2at the radial inner edge of ring 2|. 'I'he plate -22 is formed with aconcentric boss 22 which underlies the space or groove 2l between therings 2| and 22. Air communicating holes 22 are formed through the plate22 at its embossed portion thus providing air communication means fromthe groove 2l through the plate 22. It is pointed out that the metalplates 22 are subjected in service to severe strains and for that reasonmust be strong, as for example, .037" heat treated steel. 'I'heinvention also contemplates forming a bead, spinning a turned edge orotherwise modifying the edges of the sides of the holes 22 to prevent aplate rupture starting at that point and to make possible the use oflighter gauge metal for the plate 22 than otherwise would be possible.The metal composing4 the plate 22 may be treated in any satisfactorymanner to promote a good union between the rubber rings 2| and 22 andthe said plate. A good union between the rings 2| and 22 and the plate22 is important. Also the rubber of said rings may be compounded tofacilitate the union between said rings and plate all of which will beunderstood by those skilled in the compounding of rubber. The plate 22is originally formed to substantially conform to and fit upon the topsurface of the support Il and lthe top or convex surface of the discs20.

As indicated hereinbefore the discs 20 are vulcanized in molds in theusual manner of molding rubber products, the steps of which pro- Acedure are common knowledge of the rubber inf dustry and therefore arenot set out in detail.

' After a disc 22 has been molded and vulcanized angle to the plane ofthe central tube Il.

face of ring 22 is formed with a circumferene tial groove 22.

The annular metallic plate or disc 22, to which the fabric 2l isimpregnated by dipping or in any other manner found satisfactory, with athixotropic lubricant, as disclosed in my `copending application SerialNo. 462,060 led October 14, 1942.

By referring to Figs. 1 and 2 it will be seen that the rubber discs 20are disposed at an acute It will also be seen in Fig. 1 that the edge 25of the surface 22 of the fabric 21 is a sharper edge than edge 2l andthat edge 2l extends radially inwardly closer to the tube lIl than doesedge 24 when the discs 20 are in unstressed condition as shown in Fig.1.

In operation the stack of rubber discs 20 progressively change fromtheir unstressed condition shown in Fig. 1 to the compressed conditionshown in Fig. 2 and then back again to'the unstressed condition as theheads Il and Il approach and move away from each other in areciprocating motion to which vehicular suspensions are subjected aswill be understood by those familiar with the art. When an airplane orother vehicle is running on the ground the suspension springs are inconstant motion of compression or expansion strokes. Heavy vehiclessubject the suspension springs to severe compression strains and thesway and momentum of the sprung weight of the vehicle is a. severestrain on the stability of suspension springs, Then, too, and it isimportant, such suspension springs must necessarily .be of considerablelength and heretofore such springs when heavily loaded in a compressionstroke would buckle. Applicants rubber spring at the beginning of acompression stroke presents a stack oi' discs 20 with a sharp edge 2lnear or making contact with the central guide tube I As the rubber ofthe rings 2| and 22 becomes compressed between head il and head Y andbulges radially outwardly and inwardly wherever it is free to do so. Theadhesion of the rubber of each ring 2| and 22 to their metallic plates23 tends to hold the rubber in position and to prevent the rubbersdistortion and thereby substantially increases the amount of load therubber will support. As the bulge of said rubber progressively increasesit tends to close the grooves. 2li between the rings and as the discs 2lare stacked. applicant has provided means through which air in saidgrooves may escape. thus making the total space in said groovesavailable to -receive distorted rubber. 'I'he holes 38 provide the airoutlet means and it willbe seen that air in the grooves 2li will ilowahead of the rubber bulging into said grooves, the air traveling aroundthe grooves which communicate through the holes 33 and finally out tothe atmosphere through a hole 2l in the head il, said hole 26communicating with the groove 24 ofthe top disc of the stack oi discs 2dcomposing the body of the rubber spring.

The work done by rubber generates heat and heretofore it has been aproblem to be able to use a. suiliclent volume of rubber to support therequired load to which vehicular suspension springs were subjected andnot have the rubber destroyed by the heat generated. Applicantsinvention provides positive air cooling means for the rubber of thespring. While the air is forced out oi.' the grooves 2l through theopening 26 the process is reversed when the groove becomes free ofbulging rubber and fresh cool air rushes into the grooves 24 where thefresh air'becomes heated by radiation from the rubber at the sides ofsaid grooves. I'hus it will be seen that when a rubber spring embodyingthis invention is actuated, that the air within the grooves 24 is eitherpartially or wholly replaced with each stroke of the rubber spring, theamount vof air replacement depending on the length of the stroke,

Under compression ring 22 bulges radially outwardly at its outerperiphery as shown in Fig. 2. As is well known by those familiar withthe art, sharp unsupported bulging of rubber tends to destroy the rubbersubjected to such bulging. Applicant conceived the idea of relieving thelocalizing of the strain on the rubber at the periphery of the ring 22by forming a peripheral groove 28 thereon which involves substantiallythe entire outer peripheral width of the disc. Thus the rubber in theperipheral groove portion of a disc 20 will pass through a compressionperiod at the beginning of a Vcompression stroke of the spring and asthe compression continues, the rubber will be distorted into anunsupported radially outwardly extending bulge over which the rubber insaid peripheral groove portions is stretched. It will be seen that theamount of stretch and strain to which this particular portion of rubberwould otherwise be subjected is substantially relieved due to the saidperipheral groove the present invention embodies. Applicant has foundthe groove 28 effective in preventing the rubber of ring I2 fromrupturing at its outer distorted edges.

'I'he relative position of the parts constituting the assembly shown inFig. 1, wherein the spring is inits unstressed position, is such that asstated above, the edge Il is near contact, but is not pressed againstthe outer surface of the tube Il. As the bottom head I4 moves toward thehead I0 the central guide tube-constacting portions of the discs 2lslide on the surface of said tube.

6 However under the compressing effect of the movement of the head I4 inits compression stroke, the rubber in said discs is bulged radiallyinwardly toward the tube H. This results in the sharp edge IIv beingpressed and flattened against said tube I l which results in animmediate drag or resistance to the compression stroke. As the bulge ofthe said rubber increases the area oi contact of the surface Z againstthe tube il prOsressive ly increases until the discs combine to presentan unbroken contact oi the surface 2G to the tube i I. It will beunderstood that as this latter condition develops. the pressureand thearea of the surface 26 against the said tube increases, which sets up anincreasingly greater resistance to the compression stroke as itapproaches the limit of such stroke. This resistance is also affected bythe plate 2l being vulcanized to the bottom side only of each disc 20and by the disc. being at en acute angle to the plane of the tube li. Asthe sharp edge Il begins to press against tube ii in said compressionstroke, the edge drags and involves the rubber lying above it or betweenit and the plate 2! vulcanized to the disc 20 next above it. However,since the rubber between edge 35 andthe plate of the disc next above isfree to move, except for its frictional contacts, it will be seen thatthe rubber of the said portion 25, of the ring 2i, as well as a portionof the rubber of the ring 2| itself, is both drawn and compressedradially inwardly against the surface of the tube ii` when the rubberspring moves in its compression stroke and that the said contact of thediscs 20 against the guide tube sets up ahigh frictional resistance tothe compression stroke. It will now be readily seen that substantiallythe opposite frictional condition obtains in the recoil or expansionstroke. In the expanding stroke, the blunt edge 4I4 slides easily overthe surface of the tube as it simultaneously moves radially outwardlytherefrom and the slant of the conical discs extends with the directionof the drag of the surface 2B and accordingly no pointed or end portionsare being thrust endwise against said tube surface. t Thus it will beseen that the present invention provides a rubber suspension springwhich automatically involves substantial resistances to a compressionstroke which is in addition to the normal load bearing qualities of therubber used. To increase this effectiveness of the resistance to thecompression stroke and to deaden or quiet the activity of the spring,the layer of fabric 21 is impregnated Awith a thixotropic lubricant. Bythis expedient an excessive amount of action or sliding of the surface28 against the surface of the tube Il will cause said lubricant to.become viscous. Thixotropic lubricants which have been successfullyused are disclosed in my copending application referred to above. It isto be understood that the fabric 21 provides a lshock absorbing meansfor the discs 2l as well as a lubricated wearing surface.

At the beginning of the compression stroke the discs 2l compress easilyproviding a sensitive spring according to the amount and type of rubberused relative to the load. However as the compression of the rubberincreases its resistance to deflection increases, as may be seen byreference to the chart illustrating the load deflection curves shown inFig. 6. As the surface 26 of the portion 25 presses against the tube iland asthe straight sides of the grooves 24 bulge into contact as theywill do, the spring approaches the nature of a rubber bumper until nomore space is left in the groove 24 or between the tube Il and the penswhen a vehicle is driven over unusually. large bumps or into deepdepressions.

While the central guide tube Il exerts some influence in stabilizing thestack of discs 20 such means would not alone be satisfactory tol producea stable stack under high pressure. Applicant conceived the idea ofstabilizing the stack of discs 20 by the general shape of the discs andby means formed on the plates 23. Accordingly, a feature of the discs isa conical shape so that the discs can be formed into a stack by cuppingone into another. To exactly align the discs in such a stack therelatively narrow boss 32 is designed to project into the opening of theslot 24 of the next lower disc in a stack of discs forming said rubberspring. By these means the stack locks together and is stabilizedwithout the use of extraneous means.

If the plates 23 were to be omitted from the rubber spring illustratedin Fig. l and the spring were to be compressed as shown in Fig. 2, thenthe stack of rubber discs would bulge outwardly away from the guidemember II and escape from between the two heads I4 and I0. Thus it isthat the present invention makes possible the exerting of a severelongitudinal compression and pressure on a rubber spring ofsubstantiallength without bending or buckling such spring. To accomplishthis, the plates 23 are vulcanized to the bottom of the rubber rings ofthe discs 20 and as indicated hereinbefore, said plates are providedwith annular bosses 32 adapted to ilt into and cooperate with thegrooves 24 to align and then to hold the stack of discs 2l in alignment.

Each disc 20 is a separate unit in itself and is removable andreplaceable in the said stack of discs. If the rubber or a plate of adisc should fail, or if the rubber of a disc should become separatedfrom its plate, as sometimes happens when the discs have been in long,hard service, then such disc may be removed and replaced. Thisreplacement feature is important, not only as a matter of economy, butit also makes possible maintaining the rubber spring at a highefficiency level.

Referring now to Figs. 7 and 8. there is shown how a rubber springreferred to generally as Il. may be interpositioned between thesuspension arms. Il, 42, 43 and M of a military tank or a tractor 39 andthe bogie wheels ll and 33, which wheels run on a half-track 41.

Figs. 9 and 10 illustrate a spring III embodying the present inventionused as a vertical suspension spring for an automobile and beinginterposed between the arms Il and I2 of a parallelogram mechanism suchas commonly -used to position the axle and wheel of an automobile.

The rubber springs 40 and Il shown in Figs. 7 and 9 do not differ in anyessential .features of construction or operation from the spring shownin Fig. 1 and described in detail; therefore, a detailed discussion ofthe springs I0 and 5l appears to be unnecessary. These latter figuresare intended to disclose, but without limitation,l only some of the manyuses to which the invention may be adapted.

Referring to Fig. 6 the graph shows load plotted against deflection of atypical rubber spring. The curve A is produced in a testing machine byprogressive additions of load as shown by the arrows ascending on thelower edge of the shaded portion. When the desired maximum load isarrived at. the testing machine is reversed so that load isprogressively removed from the rubber spring. The relationship betweenload and deilection is then shown by the upper edge of the shadedportion and is indicated by arrows pointing downward. The differencebetween these two curves representsan area which in turn representsenergy which has, for the duration of. the test, been stored in therubber. This is commonly referred to as hysteresis, damping, or morepopularly "shock absorption." Since the function of any suspensionspring is to carry varying instantaneous loads, it becomes important tosupplement the above described static condition with loads applied inktime intervals'simulating those occurring in service (much faster thancan be applied by the conventional testing machine). Consequently, thevehicle to 'which the spring is attached is lifted upward and suddenlydropped and the instantaneous values of loads and deiiection plotted.Curve B shows such instantaneous values for a nine inch drop, and curveC for a 19 inch drop. lThe difference between the instantaneous dropvalues, curves B and C in comparison to corresponding points on curve Aserve as a criteria of the improved performance under dynamicconditions. simulating those encountered in service. The valuation maybe sum-' marized through the energy represented byl correspondingpoints, thus, B and C will carry momentary loads some 20-40 per centgreater than the static condition as indicated by A. The arearepresented by the hysteresis loop A may also include non-recoverableenergy which is' dissipated as heat through the frictional contactbetween the friction material of the inner lining of the rubber springbushing and the outer surface of the metal tube with which it engages.'I'he combination provides asimple structure having increased momentaryloadv capacity and a very much increased "shock absorber effect ascompared to that heretofore` available from any known elastic elementconstructed oi' rubber or rubber-like materials.

The invention is capable of receivinga variety of mechanical expressionssome of which., are illustrated in detail in the drawings; but it is tobe expressly understood that the drawings are for the purposes ofillustration only and are not to be construed as a deilnltion of thelimits of the invention, reference being had to the agi' pended claimsfor that purpose.

I claim: v

l. A rubber spring of the class described consisting of a plurality ofcontacting discs, each of said discs having a plurality of concentricrubber rings permanently attached to the convex surface only of arelatively thin strong conical shaped metallic plate, the concentricrubber rings of each of said discs being formed with conlcal surfacesopposite said permanently attached surfaces, each of said conicalsurfaces having frictional engagement with the confronting concavesurface of'an adjacent metallic plate.

2. In a device of the character described, a plurality of discs instacked relation, each of said discs consisting of a thin conical metalplate having a central bore, a` plurality of concentric rubber rings ofsubstantial thickness attached to the convex surface only of said plate,said rings beingradially spaced defining grooves therebetween. 3. In adevice of the character described, a

plurality oi discs in stacked relation, each of said discs consisting of.a thin conical metal plate having 4o, central bore, a plurality oiconcentric rubber rings of substantial thickness attached byvulcanization to the convex surface only oi said plate, said rings beingradially spaceddeiining a groove therebetween, each of said plateshaving a boss formed on its concave side underlying said groove andbeing adapted to project into the groove of an underlying disc of thestack.

4- In device of the character described, a plurality of discs in stackedrelation, each of said discs consisting of a thin conical metal platehaving a central bore, a plurality of concentric rub.- ber rings ofsubstantial thickness attached to the convex surface of said plate, saidrings being radially spaced denning a groove therebetween, each of saidplates having a boss formed on its concave side underlying said grooveand being adapted to project into the groove of an underllying disc ofthestack, said plate having at least one opening therethrough formed insaidboss and opening into said groove. A

5. In device oi the character described, a piurality of discs in stackedrelation, each of said discs consisting, ofa thin `conical metal platehaving a central bore. a pluralityof concentric rubf ber rings ofsubstantial thickness attached to the convex surface of said plate, saidrings being radially spaced deiininga vgroove therebetween,A each ofsaid plates having a boss formed on it's concave side 'underlying saidgroove'and being adapted to project into the'groove 'of an underlyingdisc of the stack, said-plate having at least one opening therethroughformed in 'said boss and opening into said groove, the inner ring oisaid concentric rings having va. radially ziniwardly projectingannularly extending portion of substantially reduced thickness relativeto s aid inner ring. 'l

6L In device of the character described, a plurality of discs in stackedrelation, each oi said discs consisting of a thin conical metal platehaving a central bore, a plurality of concentric rubber rings ofsubstantial thickness attached to the convex surface of said plate, saidrings being radially spaced defining a groove therebetween, each of Saidplates. having aboss formed on its concave side underlying said grooveand being adapted to project into the groove of an under? lying disc ofthe stack, said plate having at least one opening therethrough formed insaid boss and opening into said groove, the inner ring oi saidconcentric rings having a radially inwardly projecting annularlyextending portion of substan- Y tially reduced thickness relative tosaid inner ring,

i0 of friction fabric, said fabric being impregnated with a lubricant.

8. In device of thechar'acter described, a piurality of discs in stackedrelation, each of said discs consisting of a thin conical metal platehav. ing a central bore, a plurality of concentric rubber rings oi'substantial thickness attached to the convex surface of said plate,s'aid rings being I radially spaced deiining a groove therebetween,

vrality of discs in stacked relation, each of Vsaid discs consisting ora thin conical metal plate having a central bore, a plurality orconcentric rubber rings of substantialthickness attached to the convexsurface of said plate, said rings being radially spaced defining agroove therebetween,

' each of said plates having a boss iormedon its concave side underlyingsaid grooveand being adapted to project into thcgroove oi' anunderlying-disc of the stack, Vsaid platehaving at least one opening therethroughformed in Said boss and opening into seid groove. the inner ribs of said c oncentricrinss-havins a radially 1nwardly projecting annularlyextending portion or substantially reduced thickness relative to saidinner ring, said portion terminating in a layer or friction fabric, seidfabric. beingimpregnatec with athixotropic lubricant. the said inner`ring having a central opening whose sides are tapered radiallyoutwardlyl toward said metal plate.

10. In device of the character described, a p inraiity. of discs instacked relation, eachoisaid discs consisting of a thin conical metalplate having a central bore, a plurality ofconcentric rubber rings ofsubstantial thickness attached to the convexsuriace ofsaid plate, saidrings being radially spaced @encinas groove there, between, each of saidplates having a boss formed on its concave side underlying said grooveand being adapted to project into the groove oi an underlying disc ofthe stack, said plate having at least one opening therethrough formed insaid boss and opening into said groove, the inner ring of saidconcentric rings having a radially in- ^-wardly projecting annularlyextending portion rubber rings of substantial thickness attached to theconvex surface of said plate, said rings being radially spaced defininga groove therebetween, each of said plates having a boss formed on itsconcave side underlying said groove and being adapted to project intothe groove of an underlyingdisc of the stack, said plate having at leastone opening. therethrough formed in said boss and opening into saidgroove, the inner ring of said concentric rings having a radiallyinwardly projecting annularly extending portion of substantially reducedthickness relative to said inner ring, said portion terminating in alayer of substantially reduced thickness relative to said inner ring.said portion terminating in a layer .oi friction fabric, said fabricbeing impregnated with a thixotropic lubricant, the said inner ringhaving a central opening whose sides are tapered radially outwardlytoward said metal plate, the

- outer ring of said concentric rings having a circumferentiallyextending peripherial groove, said groove being a substantial portionoi.' the peripheral edge or said outer ring.

11. A rubber suspension spring for vehicles and the like comprising atop support plate attached to the body of a vehicle, a bottom supportplate attached to the running gear of said vehicle. a tubular controlguide member extending through the central portion oi said top plate andbeing iixedly attached thereto. said tubular member projectingdownwardly trom said top'plate and 11 extending through a central borein said bottom plate, said top and bottom plates having conicalsupporting faces, the supporting face of the top plate being concave andthat of the bottom convex,sa1d top and bottom supporting plates beingheldin separated relation by resilient means consisting of a pluralityof concavo-convex discs stacked in cupped relation and beinginterpositioned between said support plates, said discs having taperedcentral bores through which said tubular member projects, each of saiddiscs consisting of a plurality of concentric rubber rings ofsubstantial thickness permanently attached to .the convex surface of athin conical rigid plate,

tween, said conical metallic plates having' circumierentially extendingaligned axially pro- Jecting bosses, said bosses underlying said groovesand having at least one air communicating hole through each of saidbosses, said bottom support plate having recessed portions which receivethe said boss on the adjacent disc of said stacked discs and said topsupporting plate having an air outlet opening communicating with thegroove deilned between said concentric rings of the top disc of saidstack.

12. In a device of the character described, the combination ot avehicle, vopposed top and bottom supporting plates, said top plate beingassociated with the body and said bottom plate with the running gear ofsaid vehicle, a stack of resilient conical discs arranged in cuppedrelation interpositioned between said opposed plates, said discsconsisting of a plurality -of concentric resilient rings arranged inradially spaced relation, and rigid plates concavo-convex incross-section, with the convex sides of said plates attached to one endonly of said rings, a central bore through said discs. a cylindricalconnection member pro- 12 jected through said bore, said member beingrigidly attached to said bottom plate and pivotally mounted relative tothe lower arms of a parallelogram associated with the axle and wheel ofsaid vehicle.

13.'In combination, a supporting member, a

supported member, a spring between said members, said spring comprisinga stack of conical shaped open center discs in cupped relation, each ofsaid discs comprising a body portion of at least twov concentric ringsof rubber of substantial thickness, said rings of each disc beingpermanently attached to the convex side only of a thin metal disc, arigid guide4 member projected from said supported member into saidopenings of the discs.

14. In combination, a supporting member, a supported member, a springbetween said members, said springcomprising a stack of conical shapedopen center discs in cupped relation, each of said discs comprising abody portion of at least one ring of rubber of substantial thickness,said rubber ring' or rings of each disc being permanently attached tothe convex side only of a thin conical-shape metal disc, a rigid guidemembei` projected from said supported member into said openings of thediscs.

" ROY W. BROWN.

REFERENCES CITED The following references are of record in the ie ofthis patent:

UNITED STATES PATENTS Number Name Date 7,706 Ray Oct. 8, 1850 1,744,551Karcher Jan. 21, 1930 2,039,758 Webb May 5, 1936 2,058,623 Protzeller etal. Oct. 27, 1936 2,087,156 Johnson Jan. 16, 1940 2,215,743 Saurer Sept.24, 1940 FOREIGN PATENTS Number Country Date 134,056 v Great BritainNov. 6, 1918 432,304 Great Britain July 24, 1935 549,020 Great BritainNov. 3, i942 762,631 France Jan. 22, 1934

